8. How is radiometric age dating used to determine the age of rocks?
What limitations does this method have?

9. Why were these methods of age-dating the Earth eventually found to
be invalid?

a. Thickness of sediment

b. Salt content of the oceans (Joly)

c. Cooling rate of the Earth (Kelvin)

10. What are the standard units of geologic time commonly used by geologists?

11. Describe the process of radioactive decay, in basic terms.

12. Why is Carbon-14 a good radioisotope for dating archaeological finds?
Why is Uranium-238 a good radioisotope for dating very old rocks?

13. When in geological history did fossils "suddenly" become very abundant?
What is the probable reason why this "bloom" occurred?

14. What factors can enhance the chances of being preserved as a fossil?

15. Name the major eras of the geologic time scale. What major life
forms characterized each of these eras?

16. Name the periods of geologic time after the Precambrian.

17. What 3 sources of heat caused the Great Iron Catastrophe some 3.9
billion years ago, causing the iron in the original crust to melt and sink
to the core, creating a layered or zoned planet?

18. Name one cause for cooling of the earth's climate, which might cause
an ice age. Name one cause for warming of the earth's climate, which might
cause global warming (and melting of existing glaciers).

19. What were two of the earliest life forms found in Earth's oldest
rocks?

20. What global environmental transformation was effected by green plants?

21. What were the 2 major groups of dinosaurs?

22. What were the sea-dwelling and air-borne contemporaries of the dinosaurs?

23. Name some of the major dinosaur groups.

24. What is the currently most plausible theory explaining the extinction
of the dinosaurs and other life at the end of the Cretaceous period?

25. What was the earliest evidence of continental drift?

26. What 4 lines of evidence did Alfred Wegener use to try to prove
that all the continents were once locked together as Pangaea, 200 million
years ago?

27. What definitive evidence uncovered during the late 1960's established
the theory of plate tectonics?

28. How does seafloor spreading work? Where does the ocean floor grow
wider? Where does the ocean floor get consumed? How old is the oldest ocean
floor rock, and how do we know this? How does the age of ocean floor rock
compare with that of the continents?

29. How does the process of subduction work?

30. What key roles are played by the different densities of oceanic
vs. continental crust?

31. How does paleomagnetism work? How does it support plate tectonics?

32. What is meant by polar wandering?

33. Since the Hawaiian islands are not part of the plate margins, which
is where most of the action of plate tectonics takes place, how may their
formation be explained?

34. What internal mechanism is believed to provide the energy and movement
for the plates?

35. What is the asthenosphere? Where is it located?

36. How thick is the earth's crust, on the average? Which crust is thicker,
continental or oceanic? What rock type is each kind of crust made of?

37. Explain the difference between a convergent boundary, divergent
boundary, and transform fault. Give an example of each.

38. Give an example of each type of plate collision:

a. continental-continental

b. continental-oceanic

c. oceanic-oceanic

39. Describe the 3 types of earthquake waves, and their relative speeds.
How may they be used to calculate the distance to an earthquake?

40. What is the difference between the epicenter and the focus of an
earthquake? What do faults have to do with earthquakes?

41. Which type of seismic wave does not travel through liquids? What
does this phenomena reveal about the earth's interior? What is the "shadow
zone"?

42. How is the Richter magnitude scale interpreted? What exactly does
it measure? How is the Mercalli scale interpreted, and how does it differ
from the Richter scale?

43. What major earthquake occurred in the Illinois area in 1811-12?
What fault zone is responsible for this? What difficulties do geologists
have in trying to study it?

44. Where do about 80% of the world's earthquakes occur? What tectonic
feature is responsible for this distribution?

45. How does the history of earthquake prediction differ between the
Western world and the Far East?

46. What major objection do scientists have concerning eyewitness accounts
of abnormal animal behavior before earthquakes?

47. What pivotal event changed the opinions of many Western scientists
who were skeptical that animals behaved abnormally before earthquakes?

48. What 2 approaches were taken to try to test the responses of animals
before earthquakes?

49. After several years of testing by many scientists, what is the general
conclusion regarding the use of abnormal animal behavior as a predictor
for earthquakes?

50. According to Chinese and Japanese scientists, what time frame can
abnormal animal behavior be used as one of many earthquake precursors?